23-5 Transport in Plants - Hamilton Township High · PDF file23-5 Transport in Plants Slide 7 of 30 Copyright Pearson Prentice Hall Water Transport Transpiration In tall plants, the

Slide

1 of 30

Copyright Pearson Prentice Hall

23-5 Transport in Plants


Slide

2 of 30


Water Transport

The combination of root pressure, capillary

action, and transpiration provides enough

force to move water through the xylem

tissue of even the tallest plant.


Slide

3 of 30


Water Transport

Cohesion is the attraction of molecules of the same

substance to each other.

Adhesion is the attraction between unlike molecules.


Slide

4 of 30


Water Transport

The tendency of water to

rise in a thin tube is called

capillary action.

Water is attracted to the

walls of the tube, and

water molecules are

attracted to one another.


Slide

5 of 30


Water Transport

Capillary action causes

water to move much

higher in a narrow tube

than in a wide tube.


Slide

6 of 30


Water Transport

Tracheids and vessel elements form hollow

connected tubes in a plant.

Capillary action in these structures causes water to

rise well above the level of the ground.


Slide

7 of 30


Water Transport

Transpiration

In tall plants, the major force in water transport comes from the evaporation of water from leaves during transpiration.

When water is lost through transpiration, osmotic pressure moves water out of the vascular tissue of the leaf.

Resources/Movies/vawatert.mov


Slide

8 of 30


Water Transport

The movement of water

out of the leaf “pulls”

water upward through the

vascular system all the

way from the roots.

This process is known as

transpirational pull.


Slide

9 of 30


Water Transport

Controlling Transpiration

The water content of the leaf is kept relatively

constant.

When there is a lot of water, water pressure in the

guard cells is increased and the stomata open.

Excess water is then lost through the open

stomata by transpiration.


Slide

10 of 30


Water Transport

When water is scarce, the opposite occurs.

Water pressure in the leaf decreases. The guard cells

respond by closing the stomata.

This reduces further water loss by limiting

transpiration.

When too much water is lost, wilting occurs. When a

leaf wilts, its stomata close and transpiration slows

down. This helps a plant conserve water.

- or -

Continue to: Click to Launch:

Slide

11 of 30


23–5

../../../../Local%20Settings/Local%20Settings/Temporary%20Internet%20Files/powerbookbackup/mike%20hardy/bio%20presentation/mikesrevisedbiow-templates/My%20Documents/projects/Biology/M&L_07-08_Tech_costs/Program%20Files/QuickTake/qtake.exe

Resources/ch23_sectn05_quiz.qtb

Slide

12 of 30


23–5

In a plant stem, water moves from

a. leaves to roots through xylem.

b. roots to leaves through xylem.

c. leaves to roots through phloem.

d. roots to leaves through phloem.

Slide

13 of 30


23–5

Which of the following is NOT involved in the

movement of water in xylem tissue?

a. cohesion

b. osmosis

c. capillary action

d. adhesion

Slide

14 of 30


23–5

In very tall trees, which of the following is

primarily involved in moving water to the top of

the tree?

a. transpirational pull

b. capillary action

c. root pressure

d. osmosis